Abstract
The purpose of this study was to develop a rapid and well controlled malolactic fermentation process. Six strains of malolactic organisms were screened for morphology and growth characteristics. The Leuconostoc oenos strains PSU-1 and 8-14 exhibited the most consistent growth characteristics in complex media. Cells of strain PSU-1 grown to a concentration of 108 cells/mL, using a 14 L fermentor, were immobilized in a 3% K-carrageenan gel at a concentration of 109 to 1010 cells/mL gel. The cells, after a 24 hour activation period, were assayed for malolactic activity in a tartrate buffer, pH 4.2, 2 mM MnSO4 with malate added at 1 to 20 mM. The average specific activity found was 10 mM malate/hr/g dry cell with a Km of 5.4 mM. These results were compared to the average specific activity found for free cell suspensions of 18 mM malate/hr/g dry cell and Km of 2.0 mM. The lower rates for immobilized cells were attributed in large part to loss in cell density in the gel from 109 down to 107 cells/mL gel after immobilization. Purification of the malolactic enzyme from crude cell extract containing 0.8 units/mg protein has produced a crude enzyme preparation which showed a specific activity of 16.5 units/mg protein.
- Received July 1984.
- Copyright 1985 by the American Society for Enology and Viticulture
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